MILAN — Juventus was held to a 0-0 draw at Udinese and missed the opportunity to open up a nine-point advantage at the top of Serie A on Sunday, while Napoli closed the gap on second-placed Roma by beating Chievo Verona 2-1.
Juventus came into the game knowing it could extend its lead following Roma's 1-1 draw against Empoli on Saturday, but struggled and it was Udinese that created the better chances.
Massimiliano Allegri's men came closest when Roberto Pereyra, who is on loan from Udinese, hit the crossbar.
"It was a fair result," Allegri said. "We played badly in the first half. We gave the ball away and also risked conceding two or three times. Our difficulties stemmed from the fact that we had three defenders and (Andrea) Pirlo passing the ball and everyone else up near their area.
"We improved in the second half, getting the ball and men further forward toward their area. There are still many points up for grabs and we need to try and gain as many as possible, because points aren't enough to win the league."
Juventus was seven points ahead of Roma, with Napoli four points further back.
Elsewhere, there were setbacks for Lazio and Sampdoria in their bids for the final Champions League berth. The capital side lost 2-1 at relegation-threatened Cesena, while Sampdoria was thrashed 5-1 at Torino with Fabio Quagliarella scoring a hat trick against his old club to spoil Samuel Eto'o's debut.
Earlier, Inter Milan lost 3-1 at Sassuolo, prompting a row between the visiting fans and two of their players.
Mauricio Pinilla scored a magnificent scissor-kick volley in stoppage time against his former club to help Atalanta beat fellow struggler Cagliari 2-1. Palermo beat Hellas Verona by the same scoreline.
AC Milan hosts bottom club Parma later.
Juventus was looking for its fourth consecutive victory but was hampered by a solid Udinese performance, led by a battling Allan in midfield, who consistently got the better of Paul Pogba.
The defending champions created little of note in the first half but stepped up a gear after the break.
Carlos Tevez had a great chance to snatch the win late on after he was set up by Pogba, but sent his effort wide of the left post from 12 yards.
Napoli was looking for a third consecutive win and Rafa Benitez's side took the lead in bizarre circumstances in the 18th minute.
Manolo Gabbiadini beat the offside trap to race clear through on goal and Albano Bizzarri rushed out to clear but only succeeded in sending the ball off Bostjan Cesar's face and into the empty net.
Chievo leveled with another own goal seven minutes later when Rafael went to punch a cross but the ball ricocheted off Miguel Angel Britos and Sergio Pellissier and into the back of the net from close range. The league officially called it a Britos own goal.
Napoli scored what was to prove the winner shortly after the hour mark when Gabbiadini controlled Ivan Strinic's cross and rifled it into the bottom left corner for his first goal since joining from Sampdoria.
Cesena had only won two matches this season — both against Parma — but Gregoire Defrela gave his side a shock lead on the hour mark with a stunning 25-yard strike into the top right corner.
Cesena's second was more comical than brilliant as Defrel's cross was turned in by onrushing Lazio midfielder Danilo Cataldi.
Miroslav Klose gave Lazio hope with a volley from outside the area three minutes from time but Cesena clung on to move within four points of safety.
Lazio and Samp remained level on points, five behind Napoli.
Sassuolo had never even scored a goal against Inter and had been thrashed 7-0 in two of their past three meetings.
It was 2-0 up at halftime following brilliant strikes from Simone Zaza and Nicola Sansone.
New Inter signing Xherdan Shaqiri hit the post before Mauro Icardi gave the visitors hope when he pulled one back seven minutes from time but Domenico Berardi sealed the result in stoppage time from the penalty spot.
Young Inter defender Isaac Donkor was shown a second yellow in that incident and dismissed. Sampdoria was also down to 10 men after Sansone was sent off for a foul on Shaqiri.
Trouble continued after the final whistle with Inter players Mauro Icardi and Fredy Guarin getting into a furious row with their own fans who threw their jerseys back at them.